KR100327327B1 - Vertical diffusion furnace having improved heat loss blocking capability - Google Patents

Abstract

PURPOSE: A vertical diffusion furnace having improved heat loss blocking capability is provided to prevent the outside air under the diffusion furnace from being introduced to the inside of the diffusion furnace by installing a boat cap in a portion under the diffusion furnace. CONSTITUTION: A predetermined process for forming a thin film is performed in a reaction furnace(38). A heater(34) supplies outside heat to make the reaction furnace maintain a predetermined level of temperature. A plurality of wafers on which the thin film is to be formed are loaded into a boat. The boat cap(54) of a vacuum state is connected to the lower portion of the boat, filled with quartz wool.

Description

Vertical diffusion furnace with improved heat loss prevention

The present invention relates to a vertical diffusion furnace of a semiconductor device, and more particularly, to a vertical diffusion furnace having an improved heat loss prevention function in a diffusion furnace.

In the manufacture of highly integrated semiconductor devices, the formation of thin films is essential and important. The method of forming such a thin film is classified into two methods, namely, the interaction between the substrate and the vapor deposited material and the method of forming the film without changing the substrate material. The former is used for the formation of oxide films or nitride films of monocrystalline and polycrystalline silicon, or for the formation of silicides, and the latter is used for epitaxy, sputtering, or molecular beam epitaxy in the growth of the film by chemical vapor deposition, physical vapor deposition, or the like. However, chemical vapor deposition has been widely used in the formation of thin films because it is possible to obtain high-purity deposits, to deposit various chemical components, to be economical, and to control the process.

In recent years, vertical diffusion furnaces have been used for chemical vapor deposition, and as semiconductor devices become more integrated, the uniformity of thin films formed on wafers is reduced. The temperature, pressure, respective concentrations of reactant gases, the proportion of reactant gases, and the spacing between wafers in the formation of the oxide film are variables.

In particular, the replacement of the wafer or diffusion equipment may cause the temperature at the time of the subsequent thin film formation to be lower than that of the preceding thin film formation process. In order to prevent such heat loss, a bolt cap is used at the bottom of the diffusion furnace.

Referring to FIG. 1, a vertical diffusion furnace employing a conventional bolt cap will be described.

4 is a heater, 8 is a reactor, 12 is a quartz boat, 16 is a reaction gas inlet, 20 is a gas outlet, 24 is a boat cap, and 26 and 28 represent holes formed in the boat cap.

The reactor 8 in which the reaction for forming the thin film takes place is surrounded by a heater 4. The quartz boat 12 is composed of four boat bars in which slots are formed so that a plurality of wafers are loaded. The boat cap 24 is connected to the lower portion of the quartz boat 12. A hole 26 is formed at the boundary between the boat cap 24 and the boat 12, and a hole 28 is formed under the boat cap. The bow cap 24 is filled with quartz wool to prevent heat loss of the diffusion furnace and is in a non-vacuum state. As the cap cap 24 moves upward, the wafer is introduced into the diffusion furnace, and the reaction gas flows into the diffusion furnace through the gas inlet 16. When the predetermined reaction is completed, the bolt cap 24 moves downward to diffuse the wafer from the diffusion path, and the gas involved in the reaction is discharged to the outside through the gas outlet 20.

However, since the boat cap 24 used for preventing heat loss is in a non-vacuum state, there is no great effect on preventing heat loss, and chemicals and deionarized water are introduced into the quartz wool when the equipment is cleaned. .

In order to prevent heat loss, if the hole 28 located in the lower part of the cap cap 24 is blocked, the process temperature in the diffusion path may be prevented by replacing the equipment, but in this case, the temperature rises rather than the cap cap. There was a risk of this explosion, and a vertical diffusion furnace using a vacuum cap was not available.

Accordingly, it is an object of the present invention to provide a vertical diffusion furnace having a boat cap with improved heat loss prevention function.

In order to achieve the object of the present invention, a vertical diffusion furnace includes a reaction furnace in which a predetermined reaction for forming the thin film occurs, a heater for supplying external heat to bring the reactor to a temperature level at a predetermined level, A boat having a plurality of wafers to be formed is loaded, connected to the bottom of the boat, filled with quartz wool, and having a vacuum cap cap.

Hereinafter, the present invention will be described with reference to FIG.

34 is a heater, 38 is a reactor, 42 is a quartz boat, 46 is a reaction gas inlet, 50 is a gas outlet, 54 is a boat cap, and 56 and 58 represent holes formed in the boat cap, which are the same as those in FIG. 1, except that the inside of the boat cap 54 is vacuum.

By changing the inside of the boat cap to a vacuum state in a conventional non-vacuum frame, the thermal conductivity of the quartz wool can be reduced. That is, heat transfer between the diffusion furnace and the outside may be blocked to maintain a constant temperature in the diffusion furnace.

The table below shows the effect of the present invention by comparing the case of the inside of the boat cap with a non-vacuum and the case with a vacuum.

table

Process: GOX 160 ± 1.5Å (Temperature 820 ℃)

As can be seen in the above table, the external air at the bottom of the diffusion path is prevented from entering the diffusion path, thereby preventing heat loss. In particular, the uniformity of the film in the lower part of the diffusion furnace is superior to the effect of maintaining the temperature and improving the uniformity of the thin film than the effect in the middle or the upper part of the diffusion furnace compared to the case of using a conventional non-vacuum. Moreover, the troublesome of a washing | cleaning operation can be eliminated.

Although the present invention has been described with specific examples, it is apparent to those skilled in the art that various modifications within the essential scope of the present invention are not limited thereto.

1 is a view schematically showing a general bell spreader.

2 is a view showing a vertical diffusion furnace having an improved heat loss function.

Claims (1)

In the vertical diffusion furnace for forming a thin film, A reaction in which a predetermined reaction for forming the thin film occurs, A heater for supplying external heat to keep the reactor at a predetermined level of temperature; A boat having a plurality of wafers on which the thin film is to be formed; A vertical diffusion furnace connected to the bottom of the boat, filled with quartz wool, and having a boat cap in a vacuum state.